>Can this splitting be a problem or bug within assp or postfix?
This should be normaly no problem - but it can be one. TCP is not
controlled by assp, this is done by the OS. The TCP packet size depends on
the MTU. It is not possible to control the OS-TCP-sendbuffer and the
TCP/IP package management from the application layer of the OSI model.
If postfix is not doing a readline or getline - instead using a sysread
and does not compose the content together to check for the
<CR><LF>.<CR><LF> - it will not detect it.
Currently assp writes as much as possible to the OS socket (in to the
TCP-sendbuffer). So it may possible that the syswrite operation of assp is
splited by the OS anywhere in the <CR><LF>.<CR><LF> . An typical
TCP-sendbuffer size is 16K or 64K. So even if assp would send the
<CR><LF>.<CR><LF> in a separate syswrite operation, there is no guaranty,
that this operation leads in to a separate TCP packet at the OS site.
To prevent such a missdetection, assp does a sysread but emulates a
getline until MaxBytes are received and switches back from bulk operation
to the getline mode at the end of the mail.
I don't know if postfix uses a similar logic.
Thomas
Von: Johannes Wissen <wiss...@gmail.com>
An: assp-user@lists.sourceforge.net
Datum: 25.02.2016 10:38
Betreff: [Assp-user] "timeout exceeded" although the smtp sender
did send the final CRLF.CRLF after sending the DATA
Hello assp-users,
I am running current ASSP 2.4.7 on port 25 with postfix 2.11.3-1 behind on
port 125. Everything is running smooth, but currently I am stuck on one
eMail which is not handled correctly on port 25.
Description:
1. SMTP commands without any abnormality (EHLO, MAIL FROM, RCPT TO, DATA)
2. After the sender did finish the data, he sends <CR><LF>.<CR><LF>, as
specified.
3. However, the server seems to ignore this, after some time the "421
4.4.2
smtp-proxy.localdomain Error: timeout exceeded" message is send by the
server.
This problem occurs only for one mail between this sender and the server.
All other emails of this sender are going through fine. I now checked the
TCP Stream, the only thing I can find here is:
- the <CR><LF>.<CR><LF> is splitted into two TCP Packets. The <CR><LF>.
are
at the end of one package, after this, the next TCP Packet only contains
the 2 Bytes for the final <CR><LF>
Can this splitting be a problem or bug within assp or postfix? I can
supply
the TCP dumps and stream and also the debug assp log, if necessary.
Thanks alot for your answer.
Best regards,
--
Johannes Wissen
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